Lurasidone (Latuda®) is an atypical antipsychotic prescribed for the treatment of acute symptoms of schizophrenia. Drug adherence has been shown to be particularly low in patients with schizophrenia. Urine drug testing has been employed by behavioral health clinicians to monitor patient compliance through analysis of drugs and their major metabolites. Typically, adherence to lurasidone therapy is monitored by evaluating levels of lurasidone and one of its plasma metabolites, M11 (2-{(3,5-Dioxo-4-azatricyclo[5.2.1.02,6]dec-4-yl)methyl}cyclohexanecarboxylic acid) (see Table 1 for structure). However, these molecules are present in only low levels after dosing, thus false negative monitoring results are common. Such false negative reports can improperly induce a clinician (e.g., a physician or psychiatrist) to alter a compliant subject's lurasidone therapeutic regimen when no alteration is warranted. Improved methods for assessing and monitoring a subject's adherence to lurasidone therapy are needed.